[TEIIDDES-2771] Cannot edit Native Type extension property for procedure parameter with OUT direction - JBoss Issue Trac… has been opened to track the Designer issue.
TEIIDDES-1863 was committed in Feb. 2014, however, there was an implementation issue that prevented changing/setting the Native Type extension property for a Return parameter. (See https://issues.jboss.org/browse/TEIIDDES-2771)
Note that all parameters and columns within Designer support a standard "Native Type" property. However, to support our runtime INDEX files, a duplicate "Native Type" property was added to parameters with RETURN type. Next release will include the fix via TEIIDDES-2771